This global challenge invites people to document the wild side of their cities

What if your phone could actually help you connect with the nature all around you? During this year’s international City Nature Challenge, tens of thousands of people across the globe went outside to take photos, document and identify the wild species in their communities.

This annual competition invites people to engage with familiar outdoor spaces — from a nearby park to the streets of their neighborhood — in new ways, said Alison Young, co-director for the Center for Biodiversity and Community Science at the California Academy of Sciences. The local events hosted during the challenge, she noted, are also social opportunities for people to meet fellow nature lovers.

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“I love to hear [from participants something] like, ‘I walked through this park every single day, or I throw the ball for my dog in this park every single day, and I finally looked under a log and saw salamander, and I had no idea that we had salamanders in our city,'” Young said. The City Nature Challenge offers people “the opportunity to really slow down and harness that curiosity, and see what’s under the log,” she added.

This year, more than 66,000 participants worldwide contributed to a total of nearly 2 million observations — think plants, animals, fungi and any other living things — between April 28 and May 1, 2023. Observers documented over 57,000 species — including more than 2,570 species that are rare, threatened or endangered, Young said.

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La Paz, Bolivia, took the gold for most participants this year. Those observers also made both the highest number of observations and spotted the most species. More than 3,000 people in that city spotted 5,344 species and made over 126,000 observations collectively.

During the four-day challenge, many participants snapped photos on their smartphones and uploaded them to iNaturalist, an app designed to document and identify wildlife. (A handful of cities used other platforms.) In the days that followed, observers also had time to upload photos they had taken with other cameras and engage in a collective effort to identify each observation down to the species level, plus correct any potential misidentifications that were submitted.

People participate in the City Nature Challenge in Bergamo, Italy. Photo courtesy Alessandro Mazzoleni/City Nature Challenge

The identification step is essential — if slightly less glamorous than the actual results — to ensure that the data documented during the challenge is accurate, said Lila Higgins, co-senior manager for community science at the Natural History Museum of Los Angeles County. She and Young co-founded the City Nature Challenge.

Participants were specifically instructed to document wild species, meaning the raccoon trying to break into your garbage can would be a better find than the daffodils in your neighbor’s yard. You could still document those flowers if you wanted to, but the challenge asked users to ensure observations like those were marked as cultivated as opposed to wild.

The most observed species worldwide? The mallard, or wild duck, otherwise known by its species name, Anas platyrhynchos.

But it’s not all about spotting wildlife going about their typical days. People are invited to submit any evidence of life, from tracks to shells to scat to even roadkill.

A City Nature Challenge participant documented this reptile in Maha Sarakham, Thailand. Photo courtesy Prapasiri Warapeang/City Nature Challenge

The very first City Nature Challenge took place in 2016 and invited people in Los Angeles and San Francisco to document local nature in competition with each other over the course of eight days. In 2018, the challenge went international.

The data collected during the challenge can be used for a variety of research efforts. Young pointed to a study that used one of the City Nature Challenge’s datasets to understand urban biodiversity and land use. For Higgins, the power of the data collected during the challenge lies in its size and scope.

“We have all of these challenges — the biodiversity crisis, the climate crisis — and we are facing all these wicked big problems and we need wicked big datasets to be able to kind of ask and answer questions,” they said. “And we’re able to do that because so many people carry around these devices in their pockets. [It just] makes it so more accessible to create a dataset like this that was impossible in the past.”

A City Nature Challenge participant photographed some displeased waterfowl in Hull, England. Photo courtesy Louis Gowans/City Nature Challenge

The challenge has five major goals: connect people to urban nature, build community around nature, collect data that can be used for science, conservation and policy purposes, grow the global community of people who are interested in documenting nature and — of course — have fun, Young said.

Though the City Nature Challenge has always been a friendly competition among cities, the COVID-19 pandemic marked a shift toward a more collaborative mindset — during lockdown, Higgins said, no one was really feeling the competitive spirit. Today, competitiveness remains a welcome source of enthusiasm, but they noted that community building and reaching a common goal together are of even greater emphasis.

“Community science is all about collaboration,” Higgins said. “And we can’t ask and answer these wicked big questions without all these people working together.”